What are some alternatives?
When comparing Amazon SQS and ZeroMQ, you can also consider the following products
Apache Kafka - Apache Kafka is an open-source message broker project developed by the Apache Software Foundation written in Scala.
RabbitMQ - RabbitMQ is an open source message broker software.
IBM MQ - IBM MQ is messaging middleware that simplifies and accelerates the integration of diverse applications and data across multiple platforms.
Microsoft Azure Service Bus - Microsoft Azure Service Bus offers cloud messaging service between applications and services.
Apache ActiveMQ - Apache ActiveMQ is an open source messaging and integration patterns server.
CloudAMQP - CloudAMQP automates every part of setup, running and scaling of RabbitMQ clusters. Available on all major cloud and application platforms.